The present invention relates to a cordless telephone system and, more particularly, to a multi-channel cordless telephone system which uses a plurality of radio frequencies.
A cordless telephone system is constituted by a switching station connected to a cable telephone exchanger, and a plurality of telephone sets which are electrically connected to the switching station through radiowaves and can be freely carried in a predetermined range. A multi-channel cordless telephone system is arranged so that the switching station and the telephone sets can be connected via a plurality of radio chanhels. In a conventional multi-channel cordless telephone system, the switching station and each telephone set sequentially scan a plurality of radio channels during a standby interval. Upon calling a given telephone set, the switching station detects a nonused radio channel, and sends a calling signal over the detected nonused radio channel. A receiving telephone set always checks the presence/absence of the calling signal from the switching station by scanning the radio channels. When the receiving telephone set detects a calling signal, it stops scanning of the radio channels and sends a response signal, thereby establishing a communication link.
In the conventional connection technique, since the communication links corresponding in number to the radio channels can be established, the frequency of use of each radio channel can be averaged. However, if the number of the radio channels is increased, a time required for scanning is prolonged, and hence a time required to establish the communication link is prolonged.
Since each telephone set must scan all the channels, it cannot perform intermittent reception, and a battery life is shortened.